The present invention relates to an image transfer belt and a method of making such a belt for use in digital printing applications, and in particular, to an image transfer belt including a base film layer having perforations therein which are filled with a conductive polymer to provide controlled conductivity to the belt.
Digital imaging systems are widely used in the fields of xerography and electrography where dry or liquid toner is used to print text and graphic images. For example, systems which use digitally addressable writing heads to form latent images include laser, light-emitting diode, and electron beam printers. Copiers use optical means to form latent images. Regardless of how the latent images are formed, the images are inked (or toned), transferred, and then fixed to a paper or polymer substrate.
Digital imaging systems typically include a component such as an image transfer belt (ITB) which is utilized for latent image recording, intermediate image transfer (transfer of a toner image to the belt followed by transfer to a substrate), transfusing of toner (transport of the unfused image onto the belt with subsequent fusing), contact fusing, or electrostatic and/or frictional transport of imaging substrates such as paper, transparencies, etc.
As image transfer belts play a critical role in the imaging or substrate transport process, they must be engineered to meet exacting standards. For example, the belts must be flexible and seamless, or carefully seamed such that the seams do not interfere with image transfer. In addition, the digital printing industry also requires image transfer belts having controlled electrical conductivity and high surface planarity to achieve good image quality. Most printing applications require that the conductivity be controlled in both the dimension normal to the belt plane as well as along the belt plane.
Typical image transfer belts in use comprise a polyimide film which includes an electrically conductive material such as carbon black dispersed in the polymer. Such a polyimide film may comprise either the sole belt layer or may be used as a load bearing base layer for a compliant rubber surface layer and/or release coatings. However, a disadvantage of the use of polyimide films in image transfer belts is that they are expensive to manufacture, whether produced in a seamless loop or purchased as a web and converted to a loop through a seaming process.
Accordingly, there remains a need for an image transfer belt which exhibits controlled conductivity and which is economical to produce.